The disclosure relates to high temperature aerospace intermetallic matrix composites. More particularly, the disclosure relates to turbine engine vanes, blades, blade outer air seals (BOAS), and the like.
An attempt at intermetallic compositing via hot pressing in Dilip M. Shah and Donald L. Anton, “Alumina fiber reinforced intermetallic matrix composites”, ISSI: Structural intermetallics, 1993, pp. 755-764, TMS, Warrendale, Pa. In an exemplary process, an intermetallic is cast and powdered such as via mechanical attrition or atomization. The powder is then mixed with reinforcement fibers or into a fiber preform. The mixture is then hot pressed to fully consolidate into a composite.
Due to deficiencies in the hot pressing, an in situ formation technique has been proposed. This technique omits the fiber reinforcement. In such an in situ technique, a long rod of the intermetallic is prepared by direct casting or by powder metallurgical consolidation. The rod is reprocessed by zone melting to traverse the melt region along the rod length to cause directional solidification. The term “composite” is used due to the presence of multiple phases in a coarse microstructure causing behavior characteristic of composites.
Such an in situ technique is disclosed in Dilip M. Shah et al., “In-situ refractory intermetallic-based composites”, Materials Science and Engineering: A, Feb. 28, 1995, pp. 658-672, Volumes 192-193, Part 2, Elsevier Science S. A., Lausanne, Switzerland. An intermetallic of Nb-27Mo-27Cr-9Al-9Si (in at. %) is one identified material. Separately, an intermetallic of that Nb-27Mo-27Cr-9Al-9Si (in at. %) is discussed in Yan-Ling Hu et al., “Microstructure and phase stability in a Nb—Mo—Cr—Al—Si alloy”, Journal of Materials Science, Oct. 30, 2008 (online), pp. 7013-7025, Volume 43, Issue 22, Springer US, New York, N.Y.
Additionally, ceramic matrix composites (CMC) have been formed such as by infiltrating liquid Si (melting point 2577° F.) into an SiC fiber preform.